Innovative techniques which can continually identify vast proteome changes during tumor progression in live animals are in demand. The reciprocal effects of tumor-host interactions in the microenvironment are critical for tumor growth, invasion and metastasis. In addition to the accumulation of mutations in tumor cells, the effects from the tumor microenvironment also contribute to tumor growth and progression. The complex tumor microenvironment is virtually impossible to reproduce in vitro. A sampling technique that can continually collect proteins from mammary tumor interstitial fluid in vivo throughout tumor progression is highly desirable. This fluid represents the changes not only in the tumor cells but also within the microenvironment. It is also becoming increasingly clear that the behavior of tumors cannot be fully understood through the analysis of individual genes or proteins. Comprehensive identification of differential protein expression is needed. In this project, in vivo microdialysis combined with quantitative proteomic techniques is proposed to systematically identify the temporal secretome changes during breast tumor initiation, progression and metastases in live mouse models. Preliminary data has demonstrated the feasibility of obtaining reliable protein profiles from breast tumor interstitial fluid using in vivo microdialysis and different proteomic techniques. High-throughput identification and quantification of secretory proteins from a mouse mammary fibroblast cell line using a proteomic approach is also shown. With this innovative sampling technique and advanced proteomic platform, the current study will focus on the identification of breast tumor secretome changes temporally regulated by TGF-[unreadable] and MMP 2 during tumor progression and metastasis. Unique breast cancer mouse models previously developed in our labs provide us with valuable experimental settings. Mice with conditional knockout of Tgfbr2 (MMTV-Tgfbr2MGKO) and knockout of MMP 2 (mmp2-/-) all crossed to the MMTV-PyVmT mammary tumor model will be used. The secretory proteins associated with TGF-[unreadable] and MMP 2 during tumor progression can then be characterized. Additionally, the inter-relationships of TGF-[unreadable] and MMP 2 will be assessed. MMP 2 activity at different mammary tumor progression stages in wildtype MMTV-PyVmT live animals will also be directly measured using microdialysis and fluorogenic substrates. In conclusion, successful implementation of this innovative technology will accelerate our understanding of basic tumor biology raising the possibility for advances in the clinical treatment of breast tumor. [unreadable] [unreadable] [unreadable] [unreadable]